#define _CRT_SECURE_NO_WARNINGS 1
/********** Begin **********/
#include<stdio.h>
int main()
{
    float a = 0.0, k = 1.0; int n, c = 1;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
    {
        c *= i;
        a = (float)1 / c;
        k += a;
    }
    printf("s = %f", k);
    return 0;
}




/********** End **********/